Rythmbox does sync with the iPod (touch anyway). Just drag and drop from your PC to the device. It works very well.

I have ripped my entire CD collection to MP3 and have it on an 'always on' CentOS server at home. I have a logitech squeezebox for streaming and it sounds good (all my MP3 rips are 320).
I'b buy most of my MP3s from amazon but I do have an iTunes account, but as iTunes is basically apple formats, I try to avoid.

If I'm listening to MP3s while I'm on my PC, its just Totem that I use (default and does the trick on Ubuntu 10.04).

loebus, I love my squeezebox. I can't reccomend it enough.
You're best to have an 'always on' server with it though (I just use an old 1.2 Celeron box with extra disks and CentOS with SAMBA/HTTP access).

Subsonic is installed on it too for remote access. Subsonic is probably the best FOSS software I have ever used.
Perfectly designed. Top marks to the developer, Sindre Mehus.

I prefer to buy the CD's (hard to crash or delete a CD)
I rip it to ogg vorbis and play it on amarok ( by far to best music player even if I'm not using KDE )
I burn a copy (in K3B) and listen to that in the car because if it get's scratched I've still got the original.